In manufacturing a support for photographic paper which comprises a paper support, it is generally necessary to treat the support in one way or another so as to render the paper impermeable to water, developing agents, and auxiliaries. A method generally used for this purpose comprises overcoating the paper with a barrier layer comprising a polymer, such as a polyolefin (e.g., polyethylene) layer. When this method is used, the coated layer should preferably be as thin as possible from the viewpoints of increased productivity and reduced cost. For such thin layer coatings, however, high temperature melting of polyolefin is required. Since polyolefins are thermally decomposable, said high temperature melting tends to disadvantageously result in yellowing or pinhole formation on the coated surface. Moreover, this method does not allow the use of increased amounts of white pigments for the purpose of increasing the hiding power, since volatile matter contained in the white pigments causes foaming in the step of extrusion, or improper dispersion results. For such reasons, photographic prints high in resolving power cannot be obtained.
Recent attempts to overcome the above disadvantages involves coating a paper support with a composition which contains an unsaturated bond-containing organic compound polymerizable upon electron beam irradiation and a high concentration of an inorganic white pigment and then irradiating the thus-coated support with electron beams for curing, as described in Japanese Patent Application (OPI) Nos. 27257/82 (corresponding to U.S. Pat. No. 4, 384,040) and 49946/82 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
However, the methods disclosed in the above-cited patent specifications have either of the following drawbacks, although tending to overcome the disadvantages mentioned above.
(1) Yellowing of the support after developement occurs, which is due to retention by adsorption of chemicals used for photographic developement processing; PA0 (2) formation of cracks occur on the surface of the support upon the bending of the support. PA0 Cellulose esters; PA0 Polyvinyl butyral; PA0 Polyvinyl acetate and vinyl acetate copolymers; PA0 Saturated or unsaturated, sytrene-free polyester resins; PA0 Styrene-acrylate resins; and PA0 Polystyrene resins.
The above drawbacks (1) and (2) are contrary to each other and the prior art can hardly overcome both of them simultaneously. The photographic paper in which such support is used is therefore not totally satisfactory.